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Evening, I've got myself a set of Hope M4s, about 2.5 years old and need some TLC...I suspect they are no longer dead centre and they probably need a bleed.
For the last 4 rides if they are wet they have been screaming like a banshee so I'm convinced they need a decent bleed.
Thing is, I'm convinced a reverse bleed is actually better as it forces the crap and any air up to the lever (air naturally rises so should be esier to get rid of going bottom up).
I'm about to watch the Hope video and I'm convinced it will involve closing the bleed nipple, pumping the lever, opening the bleed nippled, closing, and repeat...I've never managed to get rid of all air doing it that way.
Before I start planning this 'military operation'...will a reverse bleed work? I think there is something special you do with the lever once you have done the bleed that involves a wee top-up but otherwise I'm thinking reverse bleed is fine apart from finding something to catch all the old brake fluid and mince that is likely to come out.
I used to bleed brakes very regularly - and it was all quite simple but I'm figuring that the process/design may have changed slightly so want to make sure I don't @rse something up doing it this way. Reverse bleed should take me about 10 minutes with care, but the top-down way tends to take me a good half hour...
Cheers.
Reverse bleed as a rule is the correct way to bleed brakes, but I can't speak for the M4- I've reverse bled V2s no bother though.
But why does squealing make you think they need bled?
Yes that's what I do 100mm syringe reverse bleed ,easy 5 min job
I reverse bleed
iirc someone said , on here, there may be an issue with the seals but I have never had any and done this for years as have friends.
The hope videe is as you describe but it making sure there is no air in the lever by rolling the diaphragm on to the lever
However the general symptom is too much lever pull or spongy brakes for needing a bleed
IME squeaks means either cold brakes or something stuck to pad o worn pads
The squealing is more just noise, but makes me think the rotor may no longer be centred between the pads. The lever isn't spongy but it isn't entirely firm, it's not been bled since I got it so I thinking if it was done, it would feel better just due to the fact it has fresh fluid in it.
I'm figuring I'll push the pads right back, unscrew the bite point and lever adjust to make them all the way out, attach the syringe, open up the nipple and give it a push (after removing the top cap and working out some kind of catchment solution - might actually put the lever on another bar so it can dribble over itself and nothing else.
My brakes are working but they aren't as sharp as they were, needing a much firmer squeeze to get a decent stopping action. Pads have >50% life in them so I don't think it's the pads entirely...I'll roughen them up again and refit and hopefully get better feeling stoppers that do stop me quicker than currently.